The present invention relates to an IC card and manufacturing method thereof.
Conventionally, for so-called IC cards have been generally and widely employed, a structure in which internal components such as electric circuit boards having specific electronic parts and the like incorporated therein are disposed in a resin frame and planar portions of the card are covered by a pair of metal panels.
It is to be noted in the present specification that the term "IC card" means a card-shaped or flat-plate-shaped object provided with an electric circuits or electronic circuits including semiconductor circuits, and it is defined that cards called by a variety of different names of PC card, modem card, LAN card, memory card, electronic card and so on having a similar basic arrangement are included in this category.
As a structure of such an IC card, and in particular, as a structure for fastening a metal panel to the frame, a variety of structures are known. For example, the document of Japanese Patent Laid-Open Publication No. HEI 9-58164 (referred to as a first prior art hereinafter) discloses an IC card in which a metal panel can be fastened to a main body frame by forming a plurality of bent portions at a peripheral edge portion of a metal panel to be fastened to the front and rear surfaces of the main body resin frame, forming a hole portion at the bent portions, inserting the bent portions into groove portions provided at the main body resin frame and implanting the bent portions while melting the resin of the frame by supersonic welding.
On the other hand, the document of Japanese Patent Laid-Open Publication No. HEI 7-160837 (referred to as a second prior art hereinafter) discloses an IC card in which an elastic tongue-like projection formed at a peripheral edge portion of a metal panel can be press-fit into a groove provided on the frame for the fastening of one metal panel to the frame, thereby achieving an engagement. This IC card employs a frame which is preparatorily integrated with a metal panel on one side of the frame.
As another structure of the IC card for press-fitting and fastening a metal panel to a frame, there is a known one in which upper and lower metal panels are fastened to an integrated frame by means of a projection formed at a peripheral edge portion of the metal panels (referred to as a third prior art hereinafter).
FIG. 18 is an exploded perspective view of an IC card 61 according to this third prior art. This IC card 61 is provided with an electric circuit board 64 incorporated with specified electronic components 65, a frame 62 which is made of resin and supports a connector 66 attached to one end side of the electric circuit board 64 and a pair of upper and lower metal panels 67 and 68 for covering a planar portion of the card on the upper surface side and the lower surface side. The connector 66 is for obtaining an electrical connection of the present IC card with a device (for example, a personal computer or the like) in which the card is used.
Side edge portions (except for the portion for attaching the connector 66) of the metal panels 67 and 68 are provided with a plurality of projections 67c and 68c obtained by bending the panel material at an angle of approximately 90 degrees, while the frame 62 is provided with a plurality of slits for allowing the lugs 67c to be received in portions corresponding to the lugs 67c and 68c on the upper surface side and the lower surface side.
FIG. 19 is a perspective view of a side portion of the frame 62 in a state before the lugs 67c of the metal panel 67 are press-fit into the slit 62g on the upper surface of the frame 62. The length of the slit 62g is set shorter than the length of the lug 67c by a specified length (for example, 0.15 mm). By forcibly press-fitting each lug 67c into the corresponding slit 62g with an external force applied, each lug 67c is press-fit in and fixed to the frame 62 with a specified fitting force. In FIG. 18, the metal panel 68 covering the reverse side of the IC card 61 is also press-fit in and fixed to the frame 62 similar to the metal panel 67 on the upper surface side.
In this IC card 61, the connector 66 attached to one end side of the frame 62 and the metal panels 67 and 68 are connected to each other by means of an adhesive sheet 69.
Further, as a means for fixing the metal panels to the frame by means of an adhesive sheet, there is a known practice of using an adhesive sheet which is formed into a frame-like shape in correspondence with the planar shape of the frame and bonding the upper and lower metal panels, the frame and connector together by means of the sheet covering approximately the entire area of the contact surfaces of them (referred to as a fourth prior art hereinafter).
However, the aforementioned prior arts have had the respective problems as follows.
That is, in the case of the aforementioned first prior art, the metal panels are welded by a supersonic wave to the frame made of resin, whereas they are welded together only at the bent portions formed at the peripheral edge portion. Therefore, it is hard to stably obtain a sufficient fixing force capable of enduring a long-term use.
On the other hand, in the case of the aforementioned second prior art, the metal panels are fixed to the frame only by the engagement of the elastic projections formed at their peripheral edge portions engaged with the grooves provided on the frame. Therefore, it is still generally hard to stably obtain a sufficient fixing force capable of enduring a long-term use.
In the case of the aforementioned third prior art, the press-fitting force effects only the lengthwise end portions of the projections 67c and 68c of the metal panels 67 and 68 and the lengthwise end portions of the slits 62g of the frame 62. Therefore, the press-fitting power is relatively weak, and it is still hard to stably obtain a sufficient fixing force capable of enduring a long-term use.
In the case of the aforementioned fourth prior art, the adhesive sheet is required to be formed into the frame-like shape corresponding to the planar shape of the frame. Therefore, the adhesive sheet itself costs much and a workability in the adhering process becomes worse, consequently leading to a disadvantage in terms of manufacturing cost.